Final answer:
Power plants contribute to thermal pollution by releasing warm water into rivers, decreasing the solubility of oxygen and thus affecting aquatic life. The warmer water causes oxygen levels to drop, leading to potential suffocation and ecosystem disruption. Cold-blooded organisms face fatal thermal stress with rising water temperatures.
Step-by-step explanation:
Power plants that discharge warm water into rivers have a negative effect on aquatic life because the higher water temperature decreases the solubility of oxygen in the water. Fish and other aquatic organisms rely on this dissolved oxygen to survive. When oxygen levels are too low, they can suffocate, leading to significant stress or death. The warmer water, being less dense, also forms a barrier on the lake or river surface, further reducing the oxygen levels and disrupting the ecosystems' health.
Moreover, many aquatic organisms are cold-blooded, meaning their body temperature is dependent on the environmental temperature. Hence, an abnormal increase can cause thermal stress, which can be fatal. This phenomenon, known as thermal pollution, underlines the importance of properly designed cooling systems in power plants to minimize ecological damage.